Attention has been paid so far to an optical disk apparatus as a replaceable medium of a large capacity. However, due to recent progress in the rapid realization of a large capacity magnetic disk apparatus, recording density is almost equal to 1 Gbits/inch.sup.2. It seems almost certain that in a few years, the optical disk apparatus will be overtaken by a magnetic disk apparatus in terms of the recording density because of a difference in the progressing speed of the realization of the large capacity. A size of a recording mark in the optical disk apparatus is expressed by the following expression 2. ##EQU1## where, .gamma. denotes a wavelength of a laser beam which is used for recording and reproducing, and NA is a numerical aperture which is expressed by NA=sin.theta. by using an angle .theta. between an optical axis and an optical axis of a light beam which has a maximum angle with the optical axis in a light that is converged by a lens. Therefore, the realization of a high density of the optical disk apparatus has progressed from four directions of a technique for forming a micro information recording mark and a technique for accurately reproducing an information recording mark smaller than a diameter of a light spot, by using the realization of a short wavelength of a semiconductor laser beam and the realization of a high NA of a condenser lens as centers. As for the first approach, in recent years, there are epoch-making advancements such as continuous oscillation at room temperature of a green laser by a semiconductor of the II-VI groups, production of a blue light emitting diode by a semiconductor of the III-V groups of the gallium nitrogen system, and the like. As for the third and fourth approaches as well, the progress is steadily being performed. However, even if they are integrated, it is presumed that the recording density can be improved by at most about one order of magnitude. A fundamental cause is because the light cannot be reduced than a wavelength of light due to a diffraction phenomenon of the light.
As a method of improving the recording density by two orders of magnitude as compared to the present situation by breaking such a limitation, attention is paid to an optical recording and reproducing method using a proximity field (evanescent field). For instance, as disclosed in Applied Physics Lettes, Vol. 61, No. 2, pp. 142-144, 1992, there has been reported an example in which a probe constructed in a manner such that a tip of an optical fiber is worked into a conical shape and regions other than a region of tens of nm of the tip are covered by a metal coating film is manufactured, the probe is mounted in a precision actuator which uses a piezoelectric element, a position is controlled, and a recording mark having a diameter of 60 nm is recorded and reproduced onto/from a multilayer film of platinum/cobalt. In case of the above example, the recording density reaches 45 Gbits/inch.sup.2 and can be increased to about 50 times as high as the present one. More recently, in Applied Physics Lettes, Vol. 65, No. 4, pp. 388-390, 1994, there has been reported an example in which, by effectively raising the numerical aperture NA by using a solid immersion lens (hereinafter, abbreviated to SIL) shown in FIG. 2, 40 Gbits/inch.sup.2 can be accomplished in principle.